This invention relates to footwear for running and specifically to improved footwear wherein the contour on the outer sole surface and associated structure produces a more efficient running action in that the runner is able to move the feet with a smoother, more efficient rolling motion along the running surface during the normal running stride.
There are many known running shoes and sole configurations which have evolved over the last 20-30 years. The object of these has been to improve the fit with the foot, reduce shoe weight and increased confort for the runner. In this prior art certain developments were intended to reduce heel shock upon landing in the foot stride and minimize the associated stress upon the various joints affected. These developments centered around improving the quality and quantity of flexible sponge material arranged between the runner's heel and the heel portion of the sole. That approach created two types of instability upon landing at the heel. The force couple to the shoe's reaction at the rear of the heel against the applied force directed through the runner's ankle was in a forward direction such as to propel the front of the shoe and the runner's foot downward causing the sole to slap the ground and send secondary shocks through the runner's lower extremities. Secondly, the thick mass of sponge material lacked lateral support and when arranged in a design with an exaggerated heel elevation made the runner prone to turning ankles when traversing uneven terrain. It is also believed that standing, walking or running with an elevated heel shoe structure is undesirable from a posture standpoint and may induce back problems with the runner. The present invention is concerned with providing a sole contour specifically adapted to efficiency and comfort in running motion. Running strides with the prior art shoes usually consisted of landing on the heel portion of the shoe after a short period with no ground contact, then moving the body weight forward over the supporting foot, and then driving the rear portion of the foot upward so that the ball and toes support the body weight with the toes in a pronounced flexed position. And, finally, springing forward off the ball and toes to a similar sequence on the other foot. In the present invention the outer sole contour is such as to cause a preferred, more efficient, smoother sequence in the running stride.
A runner equipped with the footwear of the present invention lands upon a thickened portion of the sole forward of the ankle, rolls the ankle downward and rearward to eliminate shock, and then rolls forward with the mechanical assistance from the shoe configuration to the ball and toe supporting position with the forward portion of the sole structure supporting the toes in such a way that they are noticeably straighter. Finally, the runner springs forward with considerable force and efficiency because of the relatively straighter toe position. A similar sequence is repeated on the other foot.
One result of the stride sequence when using the shoe of the present invention is the sensation of being thrown forward immediately after landing again upon "toe-off." Another result is increased leg comfort and absence of muscle fatigue and joint pain after using footwear incorporating the principles of the present invention.
The present invention is adaptable for selective tailoring of the sole configuration to favor the speed aspect of running athletics such as in foot racing, which is the sensation of being thrown forward and having ideal toe-off position and thereby to gain markedly increased stride and running speed. On the other hand, a contour of sole structure may be selected to favor the comfort aspects of running athletics such as in long, slow, distance training, and blend the forward thrust features into a shape where smooth, less forceful takeoffs are encouraged and thereby to form the most relaxing and enjoyable footwear for slower speed running.